The advent and growth of the World Wide Web and networking software enable private individuals and business personnel to access information from an increasing number of sources, such as web servers, database servers, enterprise systems, and other forms of information storage systems. The type of information available is also diverse. A user may access structured information (e.g., data stored in tables of a database) and unstructured information (e.g., Hypertext Markup Language (HTML) documents obtained from a Web server on the Internet).
The large number and types of documents available makes the search for specific or relevant information a complex and difficult task. To find such information, users often take advantage of search engines to help generate lists of potentially relevant documents. Conventional search engines allow a user to input a search request in a computer system and receive a result list of objects based on the search criteria included in the user's request. In the event the result list contains a large number of objects, the user generally has to refine the search criteria in the request to obtain a smaller result list.
To address this problem, modern search engines support the user in narrowing down a result list by providing guided navigation processes. In guided navigation, the search engine not only presents a result list, but also a number of refinement possibilities that are automatically derived from the objects in the result list. For example, in addition to presenting a list of Web pages that contain a search term provided by a user, modern Web-based search engines may also present a list of additional search terms that occur in the objects of the result list (i.e., the list of Web pages). Selecting one of these additional terms will return a new result list that includes objects matching the original search term and the selected additional term.
Other search engines provide guided navigation for certain types of structured information, such as those found in database applications. Instead of searching for a search term in an entire document, as done by Web search engines, structured-based search engines may use search criteria that require the search term to appear in an attribute of an object (i.e., “John” as the middle name in an address database). Because it is possible to display value ranges for specific database attributes, guided navigation may be more specific with these types of search engines. The value ranges may be automatically determined in order to split the result list into smaller chunks of data. The attributes provided by this form of guided navigation depend on the object type of the result objects.
Although the above-mentioned search engines provide ways to refine a result list of objects, problems arise when different objects types need to be searched using one search engine and presented in one result list. For instance, in an enterprise portal environment, a user requesting information regarding a given product may receive a result list including information reflecting technical drawings, customer order data, delivery information, meeting minutes, etc. Because the result list contains many types of objects and the attributes used for conventional guided navigation depend on the object type, current search engines do not provide guided navigation across the entire result list. Thus, there is a need for a search engine that provides guided navigation across different object types of a result list.